The invention relates to an onflow element for and installation for generating electrical energy from hydropower, wherein the onflow element comprises an onflow wall with an onflow side, as well as a free immersion edge which delimits the onflow wall. The onflow wall has a bending considered in a cross-sectional plane transverse to the free immersion edge.
The function of the onflow wall lies in the coupling of the mechanically usable power between the installation and water taking place on this. The term “water” here is to represent a fluid medium, in particular a water-containing, fluid medium that is suitable for generating electrical energy amid the utilisation of its kinetic and/or potential energy. The term “water” in particular includes drinking water, waste water, treated sewage water, process water as well as water from watercourses.
Moreover, the invention relates to an installation for generating electrical energy from hydropower, comprising a plurality of onflow elements according to the invention, which are arranged one after the other, are led in a revolving manner along a revolving direction in a closed revolving path and are drivable in the revolving direction by way of hydropower, wherein the onflow elements are led along the load section in a water guidance channel.
A multitude of devices are known, which utilise the potential drop of water or its kinetic energy, in order to generate electrical energy therefrom. In this context, one basically differentiates between two installation types.
According to a first installation type, a part of the kinetic energy of the onflowing water is utilised, in order to drive a generator for electricity production. For this, onflow elements such as turbine blades are provided, onto which water flows and which are set in motion by way of the water flow. Hydropower installations of the first type are to be found in river power stations or storage power stations. The middleshot-undershot waterwheel is also driven in this manner.
According to a second installation type, it is not primarily the kinetic energy of the onflowing water, but rather its potential energy that is released while undergoing a potential drop, which is utilised. This means that according to this principle, the gravitation force of the water acting on the onflow element drives an onflow element. This principle is utilised, for example, with an overshot waterwheel.
EP-A-1 731 756, for example, describes a hydropower installation, with which the potential energy of water is utilised for generating electrical energy. The installation comprises a hydropower unit with a vertical shaft, and a generator connected to the hydropower unit. Blades, which receive a certain volume of water, are arranged in the shaft in a manner fastened on a chain. The chain and, via this, a generator are driven by the weight of the water bearing on the blades. The installation is however comparatively inflexible with regard to its application possibilities, since these can only be carried out in combination with a vertical shaft.
WO 2011/041918 likewise describes an installation for generating electrical energy from hydropower including a revolving drive chain with a load section and return section. The drive chain is led in a revolving direction around two deflection elements that are arranged horizontally as well as vertically offset to one another. The drive chain includes a plurality of onflow elements that are arranged one after the other in the revolving direction and are spaced from one another. The drive elements in each case form part of a chain link of the drive chain. The onflow elements on the side of the load section engage into an inclined water guidance channel and with the lateral channel walls as well as the channel base form water receiving compartments. The individual water receiving compartments in the run-in region accommodate a certain volume of water, which is not let out of the water receiving compartment again until in the outlet region.
Moreover, the installation includes a generator for generating electrical energy from the revolving drive chain. The water is fed into the water guidance channel at a run-in region that is situated at a higher level, wherein the blades immersing into the water guidance channel hold back the flowing-in water, in the formed water receiving compartments. The blades are driven by the force weight of the water, by which means the water is led in the receiving compartments along the water guidance channel to an outlet opening which is situated as a lower level.
The described solution has the disadvantage that the guiding of the blades in the water guidance channel is quite imprecise, so that the receiving compartments in the movement direction are too permeable with regard to the entrained water, and a part of the entrained water runs down the water guidance channel to the outlet region, while not being utilised.